Journal

Aluminium Aviation: From Short Stirling to Airbus

Aluminium has been a vital component of aircraft construction from the earliest days of aviation.

13 April, 2016

Aircraft like the all-aluminium Spartan 7W Executive flew in the 1939 Bendix Air Races. Of the 34 7W Executives built between 1936 and 1940, 17 have survived to the present day.

In the 1930s and 1940s, aluminium aeroplanes (including the Spartan) played a central role for both sides in the Second World War. Iconic planes like the B-17 Flying Fortress, Supermarine Spitfire, and Mitsubishi A6M Zero were all built with aluminium, with new alloys and construction techniques developed to maximize survivability and weight savings. In Britain, one group of present-day volunteers is working to construct a scale replica of the front fuselage of one of these historic planes, partnering with Sapa Profiles in the UK to undertake some of this work.

Sapa, working in conjunction with the Stirling Aircraft Project, recently announced it has supplied an important extrusion that will enable the reconstruction of the Short Stirling bomber aircraft. Though more than 2,300 of these aeroplanes were built, there are no surviving examples of this important part of aviation history.

Sapa is working with the Stirling Aircraft project to build the forward fuselage section of the aircraft, including the main crew stations. Sapa supplied the extrusion for the location of the outer bomb doors, which is fitted to bottom of the fuselage bomb bay. This extrusion acts as the main keel of the fuselage, and is an essential part of the bomb bay structure.

We were extremely pleased with the support offered by Sapa Profiles UK. Following invaluable expertise during the design stage, Sapa supplied the extrusion for the outer bomb bay keel structure, without which we could not proceed to the build stage.

Richard Doel of the Stirling Project

Although there is no volume associated with this project, I feel it is Sapa's social responsibility to contribute to such projects, to recognise both the invaluable service, and in many cases, the lives given by the pilots and crews during World War Two.

Steve Nash, Sales Director, Sapa Profiles UK

The use of aluminium in aeroplanes has remained strong through the present day. The lightweight metal is a vital component of aircraft design: the A380, the world's largest passenger aeroplane, makes extensive use of aluminium alloys.

The size of the A380 (and the corresponding weight requirements) led to the development of new, dedicated alloys by the Alcan-Airbus Integrated Project Teams. 61% of the structure of the A380 is made up of aluminium alloys; the rest consists of titanium, steel, and composites.

The first flight of the A380 took place on 27th April 2005, but the discussions that would ultimately lead to the development of new alloys for the wings and fuselage of the A380 began seven years prior. In April 1998, Airbus and Alcan Aerospace (now known as Constellium) agreed to work together to develop the advanced alloys and the advanced fabrication methods needed to complete what became the A380. The brief Alcan received was to "follow as closely as possible the need for new alloys as well as the need to extend availability of existing alloys." It took until 2005 to develop, qualify and produce a full set of new alloys for the plane's wing and fuselage structures, as well as the equipment to fabricate such large structures.

The production challenges Alcan had to overcome were (literally) sizeable. Developing the ability to produce the large ingots of 7xxx aluminium alloys needed for the aeroplane's large spars, for example, was not easy. The hardware needed for the 36 metre wing panels was produced quite rapidly, but the aluminium for the spars was more of a challenge. In the late 1990s, only ingots weighing up to 22,000 lb (9,979 kg) could be cast; it took several years before the 37,000 lb (16,783 kg) ingots required for the Airbus project could be successfully produced in France. Alcan also had to develop a full series of diverse alloys for the structure of the plane's fuselage, including a 7040-T7451 plate alloy for the main frames and cockpit window frames.

After long years in development, the first commercial A380 was delivered to its new owner—Singapore Airlines—on 15 October 2007. With 13 major airlines operating the plane worldwide, an A380 takes off or lands every three minutes on average.